Mountain Triple?

Hey Guys help me out. I have a Specialized Tricross with a BB30 bottom bracket. Is it possible to use an FSA BB30 mountain triple 44/34/26 on this? If so how? and would I need a mountain or road cassette? how about derailleurs? will they shift right if I am using brifters?

Probably not. MTB cranks typically have longer spindles than road/CX bikes because the frames have slightly wider bottom brackets. You also might have some trouble getting a road front derailleur to work with the 44T big ring. MTB front derailleurs aren't compatible with brifters, though with enough fiddling you can sometimes make it work.

Cassettes and rear derailleurs are more interchangeable between MTB and road, but with some hitches. Shimano and SRAM shifters and derailleurs aren't mix-and-matchable. You also can't use the new Shimano "DynaSys" rear derailleurs with Shimano brifters. For cassettes with more than 30 teeth on the big cog you need a 9-speed MTB rear derailleur if you're using Shimano, though I think SRAM road rear derailleurs will handle that. You can mix and match Shimano brifters with 9-speed Shimano MTB rear derailleurs.

When I ride my bike I feel free and happy and strong. I'm liberated from the usual nonsense of day to day life. Solid, dependable, silent, my bike is my horse, my fighter jet, my island, my friend. Together we will conquer that hill and thereafter the world.

Probably not. MTB cranks typically have longer spindles than road/CX bikes because the frames have slightly wider bottom brackets. You also might have some trouble getting a road front derailleur to work with the 44T big ring. MTB front derailleurs aren't compatible with brifters, though with enough fiddling you can sometimes make it work.

Cassettes and rear derailleurs are more interchangeable between MTB and road, but with some hitches. Shimano and SRAM shifters and derailleurs aren't mix-and-matchable. You also can't use the new Shimano "DynaSys" rear derailleurs with Shimano brifters. For cassettes with more than 30 teeth on the big cog you need a 9-speed MTB rear derailleur if you're using Shimano, though I think SRAM road rear derailleurs will handle that. You can mix and match Shimano brifters with 9-speed Shimano MTB rear derailleurs.

I built as monster crosser that employed use of Microshift 9 speed road levers and an Acera FD - it worked just fine. RD was also fine (Deore LX) - indexing was the same on MTB and road. I used a TruVativ 44-32-22 with the 22 locked out, and it was not at all hard to do.

You will definitely need a MTB FD to make it work. Just make sure the BB shell dimensions match when trying to Frankebike your rig.

I built as monster crosser that employed use of Microshift 9 speed road levers and an Acera FD - it worked just fine. RD was also fine (Deore LX) - indexing was the same on MTB and road. I used a TruVativ 44-32-22 with the 22 locked out, and it was not at all hard to do.

If you set it up as a double then it will work because the cable pull ratio doesn't matter, but if you leave it as a triple it's tricky.

Probably not. MTB cranks typically have longer spindles than road/CX bikes because the frames have slightly wider bottom brackets. You also might have some trouble getting a road front derailleur to work with the 44T big ring. MTB front derailleurs aren't compatible with brifters, though with enough fiddling you can sometimes make it work.

Cassettes and rear derailleurs are more interchangeable between MTB and road, but with some hitches. Shimano and SRAM shifters and derailleurs aren't mix-and-matchable. You also can't use the new Shimano "DynaSys" rear derailleurs with Shimano brifters. For cassettes with more than 30 teeth on the big cog you need a 9-speed MTB rear derailleur if you're using Shimano, though I think SRAM road rear derailleurs will handle that. You can mix and match Shimano brifters with 9-speed Shimano MTB rear derailleurs.

1) Lots of cross bikes come with 46T big rings with road FD's....not sure why a 44 would be that much different?
2) New Tiagra can handle cassettes larger than 30 no?

1) Lots of cross bikes come with 46T big rings with road FD's....not sure why a 44 would be that much different?
2) New Tiagra can handle cassettes larger than 30 no?

+1

No reason a 11-32 ten speed cassette and a 44,34,26 crankset could not work with a new Tiagra or Ultegra rear derailleur.

My touring bike runs a 48,36,22 Deore Crankset with a 68mm BB shell It will accept a 12-30 nine speed using a 105 rear derailleur and a Tiagra front derailleur;

Note: a 12-27 cassette is pictured, but a Harris 12-30 also works.

Better yet is this set-up with a Deore rear derailleur that takes an 11-32 easily. The 9 speed Deore rear derailluer will work with a 10 speed cassette and brifters;

Last edited by Barrettscv; 05-10-12 at 01:46 PM.

When I ride my bike I feel free and happy and strong. I'm liberated from the usual nonsense of day to day life. Solid, dependable, silent, my bike is my horse, my fighter jet, my island, my friend. Together we will conquer that hill and thereafter the world.

1) Lots of cross bikes come with 46T big rings with road FD's....not sure why a 44 would be that much different?

A double is always more forgiving than a triple, but you could be right. It might work. It sounds like it does for Barrettscv. I just hate the sound of the chain scraping my derailleur, so I try to stick to the spec there.

Originally Posted by simonaway427

2) New Tiagra can handle cassettes larger than 30 no?

Again, possibly/probably. The new ones are spec'd for 30T max, I believe, but I've been using a Shimano RD spec'd for 27T max with a 30T cassette, so the new Tiagra may handle more. My old Tiagra RD (4500) was a bit clunky with a 32T cassette.

A double is always more forgiving than a triple, but you could be right. It might work. It sounds like it does for Barrettscv. I just hate the sound of the chain scraping my derailleur, so I try to stick to the spec there.

The FD-4603 Tiagra front derailleur work perfectly with 9-speed brifters or bar-end shifters with a nine-speed chain and a Deore MTB crankset. You do use every last mm of reach to position the derailleur cage correctly over the big chainring.

The FD-4603 Tiagra front derailleur should also shift a 10 speed chain, but might be less precise.

Last edited by Barrettscv; 05-10-12 at 01:17 PM.

When I ride my bike I feel free and happy and strong. I'm liberated from the usual nonsense of day to day life. Solid, dependable, silent, my bike is my horse, my fighter jet, my island, my friend. Together we will conquer that hill and thereafter the world.

The FD-4603 Tiagra front derailleur work perfectly with 9-speed brifters or bar-end shifters with a nine-speed chain and a Deore MTB crankset. You do use every last mm of reach to position the derailleur cage correctly over the big chainring.

I'm sure using a 22T granny ring with a 48T big ring doesn't help with the derailleur clearance.

I looked up Sheldon Brown's explanation of the limitations with mismatched derailleur to big ring size. As I thought, the main issue seems to with chain rub, not actual shifting. I tend to use the whole cassette with my middle ring, so I guess this might end up bothering me more than it might some people. Sheldon also notes that trimming becomes less of an issue as your chainstays get longer, so the Tri-Cross' geometry might help here.

Revisiting the question of using a spacer to make the FSA crank work, it looks like FSA's MTB triples have a 50mm chainline, compared to 45 for a road triple, so the rings would be 5mm further out. That also would mainly be a problem if you don't follow the recommended practice of using the small chainring with the big cogs and vice versa.

So, I guess a lot of what I said in my first post is entirely debatable.

I'm sure using a 22T granny ring with a 48T big ring doesn't help with the derailleur clearance.

I looked up Sheldon Brown's explanation of the limitations with mismatched derailleur to big ring size. As I thought, the main issue seems to with chain rub, not actual shifting. I tend to use the whole cassette with my middle ring, so I guess this might end up bothering me more than it might some people. Sheldon also notes that trimming becomes less of an issue as your chainstays get longer, so the Tri-Cross' geometry might help here.

There are five or more potential issues;

The cage is designed for a certain maximum ring size. Tiagra and 105 are designed for a 50t. Ultegra: 52. MTB derailleurs are designed for 48-44t chainring sizes. Here is an Ultegra FD with a 46t chainring, the fit is not good to look at, but it shifts well anyway;

The parallelogram is designed for a certain chainring set. Ultegra: 52, 39, 30. 105 & Tiagra: 50, 39, 30. MTB 48-46, 36, 26 or 44, 34, 24. I use a chain-catcher on all my triples which helps to direct the chain towards the small chainring while downshifting.

Cable pull is either road or MTB

The front derailleur has a limited travel and reach. The reach required is greater on a MTB crankset than on a road crankset.

The ring size differential (large chainring minus small chainring) matters when trying to exceed factory specifications. I've had no problem with a 26 unit differential.

I have several extremely wide-range drivetrains, including a 50, 39 & 26t triple with 12-30 ten-speed cassette and the 48, 36 & 22t Deore triple with 11-32 nine-speed cassette. I'm able to use brifters and all gear combinations without any issues. The only combination I avoid is the Big-Big combo. It will work without complaints, but I know the chainline is ugly and I should be using the middle chainring at that speed.

Last edited by Barrettscv; 05-11-12 at 07:09 AM.

When I ride my bike I feel free and happy and strong. I'm liberated from the usual nonsense of day to day life. Solid, dependable, silent, my bike is my horse, my fighter jet, my island, my friend. Together we will conquer that hill and thereafter the world.

None of this is as complicated as it sounds. I am running Truvativ x9 10s double with bb spacers. 11-32 9s cassette with 105 deraileurs and ultegra brifters. You can mix and match a lot more than people will tell you is possible.

Hmm, not sure if this helps at all, but I used a mtb triple, with no granny gear, a mtb front and triple sora level shifters. I limited the cable pull on the deraileur and had no issues. Was set as 44/34. 8 speed with a tiagra rear and mtb cassette.

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